It is proposed to develop a genetic analytic system in Chlamydomonas reinhardi to study structure, function, chemical organization, and morphogenesis of microtubular structures. The analytic stystem under development makes use of temperature-sensitive conditonal mutations affecting flagellar activity and cell division. Temperature shift experiments, in which exponential cultures of mutant organisms are transferred from low (permissive) temperatures to high (restrictive) temperatures, reveal two levels of genetic control of flagellar function: 1) primary control - involving structure of proteins directly involved in function, and 2) secondary control -involving factors required for reassembly of flagella following deflagellation or associated with redevelopment of flagella following cell division. The first category of mutants will be used, in conjunction with isolation of flagella and analysis of constituent proteins, to study the chemical organization of flagella. The second category of mutants will be used to study the flagellar morphogenesis, and non-chromosomal determinants of function of basal bodies. A class of conditional non-dividing strains is under investigation as suitable material for studying function and morphogenisis of mitotic and cytokinetic microtubules.